“Except our own thoughts, there is nothing absolutely in our power.”

The destruction of the foundations necessarily brings down the whole edifice.

For to be possessed of a vigorous mind is not enough; the prime requisite is rightly to apply it.

For the very fact that my knowledge is increasing little by little is the most certain argument for its imperfection.

At last I will devote myself sincerely and without reservation to the general demolition of my opinions.

I had become aware, as early as my college days, that no opinion, however absurd and incredible can be imagined, that has not been held by one of the philosophers.

To know what people really think, pay attention to what they do, rather than what they say.

Let whoever can do so deceive me, he will never bring it about that I am nothing, so long as I continue to think I am something.

Am I so tied to a body and senses that I am incapable of existing without them?

Each problem that I solved became a rule which served afterwards to solve other problems.

The first precept was never to accept a thing as true until I knew it as such without a single doubt

Masked, I advance.

There is nothing more ancient than the truth.

When it is not in our power to determine what it true, we ought to follow what is most probable.

For I found myself embarrassed with so many doubts and errors that it seemed to me that the effort to instruct myself had no effect other than the increasing discovery of my own ignorance

All that is necessary to right action is right judgment, and to the best action the most correct judgment.

I desire to live in peace and to continue the life I have begun under the motto ‘to live well you must live unseen’.